Instructions for Use (IFU) for SLS Printing

This document provides technology-specific instructions for Selective Laser Sintering (SLS) printing workflows using 3Dresyns® powders and, where applicable, 3Dresyns® binders, auxiliaries and support materials.

3Dresyns SLS powders for Selective Laser Sintering (SLS) printing — Nylon 11 (white), Nylon 12 (white), and Thermoplastic Elastomer TPE (black) — have been designed to exhibit printing behavior equivalent to commercial SLS powders with the same composition and color.

Our SLS powders (Nylon 11, Nylon 12 and TPE – PEBA type) can therefore be used as direct replacements, using the same printing parameters as equivalent commercial products, without requiring complex recalibration. These fast and accurate Instructions for Use (IFU) apply to most open-parameter SLS printers.

This IFU applies exclusively to powder-based SLS processes and is fundamentally different from IFUs for vat photopolymerization (SLA, DLP, LCD) or inkjet printing.

This IFU must be used in conjunction with

Printer-specific documentation provided by the SLS equipment manufacturer
Powder material datasheets and safety documentation
Any application-specific technical documentation supplied by 3Dresyns

This document does not replace manufacturer instructions for SLS systems.

Scope of application

This IFU applies to:

Selective laser sintering (SLS) systems
Polymer, composite, metal or ceramic powder processing routes
SLS workflows using powders and, where applicable, binders, auxiliaries or process aids supplied by 3Dresyns

This IFU does not apply to:

Vat photopolymerization technologies
Inkjet binder jetting unless explicitly stated
Extrusion-based or filament-based technologies

Nature of SLS printing processes

Selective Laser Sintering is a powder-bed fusion technology in which a laser selectively fuses powder particles layer by layer. Material behavior in SLS is highly process-dependent.

Final part properties depend on:

Powder composition, particle size and morphology
Laser energy density and scan strategy
Layer thickness and recoating behavior
Powder bed temperature and atmosphere
Post-processing and thermal treatment

Powder material considerations

Powders used in SLS printing:

Must meet defined particle size and flowability requirements
Must be compatible with the selected laser wavelength and energy input
May exhibit different sintering windows and thermal responses

Powder reuse, aging and contamination can significantly affect print quality and reproducibility.

SLS printing settings: main variables

Key parameters influencing SLS printing include:

Powder bed temperature
Laser power and scan speed
Hatch spacing and scan strategy
Layer thickness
Build chamber temperature and environment
Optional use of laser-absorbing additives

Improper parameter selection may result in incomplete sintering, warping, porosity or surface defects.

Powder bed temperature adjustment

Correct bed temperature must be set within the sintering window, i.e. the temperature range where powder particles fuse effectively.
Too high bed temperature: over-melting, loss of dimensional accuracy, part deformation.
Too low bed temperature: insufficient sintering, weak interlayer bonding, poor mechanical properties or print failure.

Laser power and scan speed adjustment

Sintering occurs due to laser energy absorption by the powder.
Lower laser power typically requires slower scan speeds.
Higher laser power allows faster scan speeds at a given bed temperature.
Too low laser power and/or too high scan speed: poor fusion, delamination and weak cohesion.
Too high laser power and/or too low scan speed: loss of dimensional accuracy and increased brittleness.

Adjustment using laser-absorbing additives

Laser-absorbing additives (e.g. carbon black) can be added at low dosages (typically 1–5%) to improve laser absorption in powders with low absorption efficiency.
This approach is particularly useful for slow-sintering powders or custom powder blends.

Optimization is straightforward for widely used polymers such as nylons, but becomes essential when working with exotic materials, custom blends, or Cold Metal, Ceramic, Polymer & Exotic Powders Fusion. For more information, read: IFU for SLS – Cold Fusion of Metal, Ceramic and Exotic Powders.

Calibration test

Calibrate your SLS printer using 3Dtest1 (3Dresyns flat coin) for rapid optimization of resolution and printing parameters.
Each SLS printer requires specific settings depending on powder composition, molecular structure and physicochemical properties.
Slice the 3Dtest1 STL file using the settings of the closest equivalent commercial powder.
Upload the sliced file and print.

Design and build considerations

SLS allows printing without support structures; however:

Part orientation affects thermal gradients and distortion
Wall thickness and geometry influence heat dissipation
Enclosed volumes may trap unsintered powder

Design for SLS should consider post-processing and depowdering requirements.

Post-processing and finishing

After printing, allow the build chamber to cool completely before part removal to prevent warping.
Remove parts from the powder bed.
Remove excess unfused powder manually and/or using compressed air.
If surface smoothing is required, use Cleaning Fluid WS1.
Recycle unfused powder by sieving and mixing it with fresh powder for subsequent print jobs.

Dimensional accuracy and shrinkage

SLS parts may exhibit:

Anisotropic shrinkage
Dimensional variation due to thermal history

Users must:

Account for shrinkage during design
Validate dimensional accuracy experimentally

Calibration and compensation strategies are application-specific.

Handling, safety and environmental considerations

Powder-based SLS workflows introduce specific risks, including:

Dust generation and inhalation hazards
Flammability or reactivity of certain powders
High-temperature equipment

Users must follow appropriate safety procedures, including:

Use of personal protective equipment
Proper ventilation and dust control
Compliance with local safety and environmental regulations

Validation, qualification and responsibility

SLS parts are highly process-dependent. Users are responsible for:

Validating process parameters for their specific powder and equipment
Qualifying post-processing and thermal treatments
Ensuring suitability for the intended application

3Dresyns does not assume responsibility for performance obtained under user-defined SLS workflows.

Relationship to other Instructions for Use

This IFU is specific to Selective Laser Sintering (SLS) and must not be confused with IFUs for vat photopolymerization or inkjet printing. Where binders, auxiliaries or additives are used, the relevant technical documentation applies. In case of discrepancy, the most technology-specific documentation prevails.

Governing principle

Selective Laser Sintering is a multivariable, process-driven manufacturing technology. Final part performance depends on powder properties, laser parameters, thermal history and post-processing conditions and must be validated by the user.